The focus of this project is the development of appropriate statistical methodologies for analysis of molecular genetic data from a variety of biological systems. Investigations continued into the modeling and analysis of data from developmental toxicity experiments, with specific attention directed at the dominant lethal assay in the male mouse. Statistical methods for analyzing data from this type of assay when the treatment is comprised of two distinct stimuli were considered, to assess possible "synergy" between the stimuli. Various forms of such analyses were compared to identify which of the methods provide optimal statistical characteristics, such as minimal type I error, and maximal power. Investigations also continued into the examination and analysis of genetic susceptibility in animal and human subjects. Statistical models and methods were identified for assessing gene-environment interactions; these include logistic regression, complimentary log regression, and other generalized linear models.